/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved. ORACLE PROPRIETARY/CONFIDENTIAL. Use is
 * subject to license terms.
 */

package java.lang;

/**
 *
 * The {@code Byte} class wraps a value of primitive type {@code byte} in an object. An object of type {@code Byte}
 * contains a single field whose type is {@code byte}.
 *
 * <p>
 * In addition, this class provides several methods for converting a {@code byte} to a {@code String} and a
 * {@code String} to a {@code
 * byte}, as well as other constants and methods useful when dealing with a {@code byte}.
 *
 * @author Nakul Saraiya
 * @author Joseph D. Darcy
 * @see java.lang.Number
 * @since JDK1.1
 */
public final class Byte extends Number implements Comparable<Byte> {

    /**
     * A constant holding the minimum value a {@code byte} can have, -2<sup>7</sup>.
     */
    public static final byte MIN_VALUE = -128;

    /**
     * A constant holding the maximum value a {@code byte} can have, 2<sup>7</sup>-1.
     */
    public static final byte MAX_VALUE = 127;

    /**
     * The {@code Class} instance representing the primitive type {@code byte}.
     */
    @SuppressWarnings("unchecked")
    public static final Class<Byte> TYPE = (Class<Byte>) Class.getPrimitiveClass("byte");

    /**
     * Returns a new {@code String} object representing the specified {@code byte}. The radix is assumed to be 10.
     *
     * @param b the {@code byte} to be converted
     * @return the string representation of the specified {@code byte}
     * @see java.lang.Integer#toString(int)
     */
    public static String toString(byte b) {
        return Integer.toString((int) b, 10);
    }

    private static class ByteCache {
        private ByteCache() {
        }

        static final Byte cache[] = new Byte[-(-128) + 127 + 1];

        static {
            for (int i = 0; i < cache.length; i++)
                cache[i] = new Byte((byte) (i - 128));
        }
    }

    /**
     * Returns a {@code Byte} instance representing the specified {@code byte} value. If a new {@code Byte} instance is
     * not required, this method should generally be used in preference to the constructor {@link #Byte(byte)}, as this
     * method is likely to yield significantly better space and time performance since all byte values are cached.
     *
     * @param b a byte value.
     * @return a {@code Byte} instance representing {@code b}.
     * @since 1.5
     */
    public static Byte valueOf(byte b) {
        final int offset = 128;
        return ByteCache.cache[(int) b + offset];
    }

    /**
     * Parses the string argument as a signed {@code byte} in the radix specified by the second argument. The characters
     * in the string must all be digits, of the specified radix (as determined by whether
     * {@link java.lang.Character#digit(char, int)} returns a nonnegative value) except that the first character may be
     * an ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to indicate a negative value or an ASCII plus sign
     * {@code '+'} ({@code '\u005Cu002B'}) to indicate a positive value. The resulting {@code byte} value is returned.
     *
     * <p>
     * An exception of type {@code NumberFormatException} is thrown if any of the following situations occurs:
     * <ul>
     * <li>The first argument is {@code null} or is a string of length zero.
     *
     * <li>The radix is either smaller than {@link java.lang.Character#MIN_RADIX} or larger than
     * {@link java.lang.Character#MAX_RADIX}.
     *
     * <li>Any character of the string is not a digit of the specified radix, except that the first character may be a
     * minus sign {@code '-'} ({@code '\u005Cu002D'}) or plus sign {@code '+'} ({@code '\u005Cu002B'}) provided that the
     * string is longer than length 1.
     *
     * <li>The value represented by the string is not a value of type {@code byte}.
     * </ul>
     *
     * @param s the {@code String} containing the {@code byte} representation to be parsed
     * @param radix the radix to be used while parsing {@code s}
     * @return the {@code byte} value represented by the string argument in the specified radix
     * @throws NumberFormatException If the string does not contain a parsable {@code byte}.
     */
    public static byte parseByte(String s, int radix) throws NumberFormatException {
        int i = Integer.parseInt(s, radix);
        if (i < MIN_VALUE || i > MAX_VALUE)
            throw new NumberFormatException("Value out of range. Value:\"" + s + "\" Radix:" + radix);
        return (byte) i;
    }

    /**
     * Parses the string argument as a signed decimal {@code
     * byte}. The characters in the string must all be decimal digits, except that the first character may be an ASCII
     * minus sign {@code '-'} ({@code '\u005Cu002D'}) to indicate a negative value or an ASCII plus sign {@code '+'}
     * ({@code '\u005Cu002B'}) to indicate a positive value. The resulting {@code byte} value is returned, exactly as if
     * the argument and the radix 10 were given as arguments to the {@link #parseByte(java.lang.String, int)} method.
     *
     * @param s a {@code String} containing the {@code byte} representation to be parsed
     * @return the {@code byte} value represented by the argument in decimal
     * @throws NumberFormatException if the string does not contain a parsable {@code byte}.
     */
    public static byte parseByte(String s) throws NumberFormatException {
        return parseByte(s, 10);
    }

    /**
     * Returns a {@code Byte} object holding the value extracted from the specified {@code String} when parsed with the
     * radix given by the second argument. The first argument is interpreted as representing a signed {@code byte} in
     * the radix specified by the second argument, exactly as if the argument were given to the
     * {@link #parseByte(java.lang.String, int)} method. The result is a {@code Byte} object that represents the
     * {@code byte} value specified by the string.
     *
     * <p>
     * In other words, this method returns a {@code Byte} object equal to the value of:
     *
     * <blockquote> {@code new Byte(Byte.parseByte(s, radix))} </blockquote>
     *
     * @param s the string to be parsed
     * @param radix the radix to be used in interpreting {@code s}
     * @return a {@code Byte} object holding the value represented by the string argument in the specified radix.
     * @throws NumberFormatException If the {@code String} does not contain a parsable {@code byte}.
     */
    public static Byte valueOf(String s, int radix) throws NumberFormatException {
        return valueOf(parseByte(s, radix));
    }

    /**
     * Returns a {@code Byte} object holding the value given by the specified {@code String}. The argument is
     * interpreted as representing a signed decimal {@code byte}, exactly as if the argument were given to the
     * {@link #parseByte(java.lang.String)} method. The result is a {@code Byte} object that represents the {@code byte}
     * value specified by the string.
     *
     * <p>
     * In other words, this method returns a {@code Byte} object equal to the value of:
     *
     * <blockquote> {@code new Byte(Byte.parseByte(s))} </blockquote>
     *
     * @param s the string to be parsed
     * @return a {@code Byte} object holding the value represented by the string argument
     * @throws NumberFormatException If the {@code String} does not contain a parsable {@code byte}.
     */
    public static Byte valueOf(String s) throws NumberFormatException {
        return valueOf(s, 10);
    }

    /**
     * Decodes a {@code String} into a {@code Byte}. Accepts decimal, hexadecimal, and octal numbers given by the
     * following grammar:
     *
     * <blockquote>
     * <dl>
     * <dt><i>DecodableString:</i>
     * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
     * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
     * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
     * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
     * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
     *
     * <dt><i>Sign:</i>
     * <dd>{@code -}
     * <dd>{@code +}
     * </dl>
     * </blockquote>
     *
     * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> are as defined in section 3.10.1 of <cite>The
     * Java&trade; Language Specification</cite>, except that underscores are not accepted between digits.
     *
     * <p>
     * The sequence of characters following an optional sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
     * "{@code #}", or leading zero) is parsed as by the {@code
     * Byte.parseByte} method with the indicated radix (10, 16, or 8). This sequence of characters must represent a
     * positive value or a {@link NumberFormatException} will be thrown. The result is negated if first character of the
     * specified {@code String} is the minus sign. No whitespace characters are permitted in the {@code String}.
     *
     * @param nm the {@code String} to decode.
     * @return a {@code Byte} object holding the {@code byte} value represented by {@code nm}
     * @throws NumberFormatException if the {@code String} does not contain a parsable {@code byte}.
     * @see java.lang.Byte#parseByte(java.lang.String, int)
     */
    public static Byte decode(String nm) throws NumberFormatException {
        int i = Integer.decode(nm);
        if (i < MIN_VALUE || i > MAX_VALUE)
            throw new NumberFormatException("Value " + i + " out of range from input " + nm);
        return valueOf((byte) i);
    }

    /**
     * The value of the {@code Byte}.
     *
     * @serial
     */
    private final byte value;

    /**
     * Constructs a newly allocated {@code Byte} object that represents the specified {@code byte} value.
     *
     * @param value the value to be represented by the {@code Byte}.
     */
    public Byte(byte value) {
        this.value = value;
    }

    /**
     * Constructs a newly allocated {@code Byte} object that represents the {@code byte} value indicated by the
     * {@code String} parameter. The string is converted to a {@code byte} value in exactly the manner used by the
     * {@code parseByte} method for radix 10.
     *
     * @param s the {@code String} to be converted to a {@code Byte}
     * @throws NumberFormatException If the {@code String} does not contain a parsable {@code byte}.
     * @see java.lang.Byte#parseByte(java.lang.String, int)
     */
    public Byte(String s) throws NumberFormatException {
        this.value = parseByte(s, 10);
    }

    /**
     * Returns the value of this {@code Byte} as a {@code byte}.
     */
    public byte byteValue() {
        return value;
    }

    /**
     * Returns the value of this {@code Byte} as a {@code short} after a widening primitive conversion.
     * 
     * @jls 5.1.2 Widening Primitive Conversions
     */
    public short shortValue() {
        return (short) value;
    }

    /**
     * Returns the value of this {@code Byte} as an {@code int} after a widening primitive conversion.
     * 
     * @jls 5.1.2 Widening Primitive Conversions
     */
    public int intValue() {
        return (int) value;
    }

    /**
     * Returns the value of this {@code Byte} as a {@code long} after a widening primitive conversion.
     * 
     * @jls 5.1.2 Widening Primitive Conversions
     */
    public long longValue() {
        return (long) value;
    }

    /**
     * Returns the value of this {@code Byte} as a {@code float} after a widening primitive conversion.
     * 
     * @jls 5.1.2 Widening Primitive Conversions
     */
    public float floatValue() {
        return (float) value;
    }

    /**
     * Returns the value of this {@code Byte} as a {@code double} after a widening primitive conversion.
     * 
     * @jls 5.1.2 Widening Primitive Conversions
     */
    public double doubleValue() {
        return (double) value;
    }

    /**
     * Returns a {@code String} object representing this {@code Byte}'s value. The value is converted to signed decimal
     * representation and returned as a string, exactly as if the {@code byte} value were given as an argument to the
     * {@link java.lang.Byte#toString(byte)} method.
     *
     * @return a string representation of the value of this object in base&nbsp;10.
     */
    public String toString() {
        return Integer.toString((int) value);
    }

    /**
     * Returns a hash code for this {@code Byte}; equal to the result of invoking {@code intValue()}.
     *
     * @return a hash code value for this {@code Byte}
     */
    @Override
    public int hashCode() {
        return Byte.hashCode(value);
    }

    /**
     * Returns a hash code for a {@code byte} value; compatible with {@code Byte.hashCode()}.
     *
     * @param value the value to hash
     * @return a hash code value for a {@code byte} value.
     * @since 1.8
     */
    public static int hashCode(byte value) {
        return (int) value;
    }

    /**
     * Compares this object to the specified object. The result is {@code true} if and only if the argument is not
     * {@code null} and is a {@code Byte} object that contains the same {@code byte} value as this object.
     *
     * @param obj the object to compare with
     * @return {@code true} if the objects are the same; {@code false} otherwise.
     */
    public boolean equals(Object obj) {
        if (obj instanceof Byte) {
            return value == ((Byte) obj).byteValue();
        }
        return false;
    }

    /**
     * Compares two {@code Byte} objects numerically.
     *
     * @param anotherByte the {@code Byte} to be compared.
     * @return the value {@code 0} if this {@code Byte} is equal to the argument {@code Byte}; a value less than
     *         {@code 0} if this {@code Byte} is numerically less than the argument {@code Byte}; and a value greater
     *         than {@code 0} if this {@code Byte} is numerically greater than the argument {@code Byte} (signed
     *         comparison).
     * @since 1.2
     */
    public int compareTo(Byte anotherByte) {
        return compare(this.value, anotherByte.value);
    }

    /**
     * Compares two {@code byte} values numerically. The value returned is identical to what would be returned by:
     * 
     * <pre>
     * Byte.valueOf(x).compareTo(Byte.valueOf(y))
     * </pre>
     *
     * @param x the first {@code byte} to compare
     * @param y the second {@code byte} to compare
     * @return the value {@code 0} if {@code x == y}; a value less than {@code 0} if {@code x < y}; and a value greater
     *         than {@code 0} if {@code x > y}
     * @since 1.7
     */
    public static int compare(byte x, byte y) {
        return x - y;
    }

    /**
     * Converts the argument to an {@code int} by an unsigned conversion. In an unsigned conversion to an {@code int},
     * the high-order 24 bits of the {@code int} are zero and the low-order 8 bits are equal to the bits of the
     * {@code byte} argument.
     *
     * Consequently, zero and positive {@code byte} values are mapped to a numerically equal {@code int} value and
     * negative {@code
     * byte} values are mapped to an {@code int} value equal to the input plus 2<sup>8</sup>.
     *
     * @param x the value to convert to an unsigned {@code int}
     * @return the argument converted to {@code int} by an unsigned conversion
     * @since 1.8
     */
    public static int toUnsignedInt(byte x) {
        return ((int) x) & 0xff;
    }

    /**
     * Converts the argument to a {@code long} by an unsigned conversion. In an unsigned conversion to a {@code long},
     * the high-order 56 bits of the {@code long} are zero and the low-order 8 bits are equal to the bits of the
     * {@code byte} argument.
     *
     * Consequently, zero and positive {@code byte} values are mapped to a numerically equal {@code long} value and
     * negative {@code
     * byte} values are mapped to a {@code long} value equal to the input plus 2<sup>8</sup>.
     *
     * @param x the value to convert to an unsigned {@code long}
     * @return the argument converted to {@code long} by an unsigned conversion
     * @since 1.8
     */
    public static long toUnsignedLong(byte x) {
        return ((long) x) & 0xffL;
    }

    /**
     * The number of bits used to represent a {@code byte} value in two's complement binary form.
     *
     * @since 1.5
     */
    public static final int SIZE = 8;

    /**
     * The number of bytes used to represent a {@code byte} value in two's complement binary form.
     *
     * @since 1.8
     */
    public static final int BYTES = SIZE / Byte.SIZE;

    /** use serialVersionUID from JDK 1.1. for interoperability */
    private static final long serialVersionUID = -7183698231559129828L;
}
